Anthelmintic spiroketals and method of use

ABSTRACT

This invention pertains to a new method for killing and controlling worms (Helminths), new formulations for killing and controlling worms in animals, new chemical compounds, and a new synthesis of northern hemisphere intermediates for the synthesis of milbemycin and avermectin macrolides.

This application is a division of application Ser. No. 757,660 filedJuly 22, 1985, now U.S. Pat. No. 4,686,287.

SUMMARY OF THE INVENTION

This invention pertains to a new method for killing and controllingworms (Helminths), new formulations for killing and controlling worms inanimals, new chemical compounds, and a new synthesis of northernhemisphere intermediates for the synthesis of milbemycin and avermectinmacrolides.

The anthelmintic spiroketals have the general structural formula XIX.

BACKGROUND OF THE INVENTION

The milbemycins and avermectins are a series of macrolide antibioticsknown to have closely related chemical structures and to exhibit highlypotent anthelimintic, insecticidal, ectoparasiticidal and acaricidalactivity. See M. H. Fisher and H. Mrozik, The Avermectin Family ofMacrolide-Like Antibiotics, pp. 553-606, Macrolide Antibiotics:Chemistry, Biology, and Practice, ed. S. Omura, Academic Press (1984).

The known preparative procedures for these macrolides have employedfermentation techniques or lengthy syntheses unsuitable for preparationof various analogs.

The fermentation and isolation procedures, and the chemical structuresand properties of the milbemycins and avermectins, are more fullydescribed in U.S. Pat. Nos. 3,950,360; 3,984,564; 3,992,551; 4,093,629;and 4,144,352; Tetrahedron Letters, No. 10, pages 711-714, 1975; Journalof Antibiotics, Vol. 29, No. 6, June, 1976, pages 76-35 to 76-42 andpages 76-14 to 76-16; Antimicrobial Agents and Chemotherapy, Volume 15,No. 3, March 1979; pages 361-367; and Journal of Antibiotics, Volume 33,No. 10, October, 1980, pages 1120-1127.

The total synthesis of milbemycin β₃ is described in D. R. Williams etal., J. Am. Chem. Soc., 104, 4708-4710 (1982) and A. B. Smith et al., J.Am. Chem. Soc., 104, 4015-4018 (1982).

A lengthy synthesis of milbemycin β₃ is also described in InternationalPatent Application No.: PCT/US/82/01658, filed 22 Nov. 1982 and U.S.Pat. No. 4,408,059. At column 7, lines 42-51 of U.S. Pat. 4,408,059 theapplicants speculate that a number of compounds, particularly thespiroketal compounds of Formula XXIV, include the chemical structureresponsible for the biological activity of the various milbemycin andavermectin macrolides, and hence may themselves have utility asanthelmintic, insecticidal, ectoparasiticidal or acaricidal agentssignificantly simplified in chemical structure in comparison with theprior art compounds exhibiting similar biological activity.

The literature contains a number of syntheses of the1,7-dioxaspiro[5.5]undecane system, many of which depend on theconstruction of a 1,9-dihydroxy-5-oxononane followed by intramolecularketalization to generate the spiroketal. See, for example, K. Mori andK. Tanida, Synthesis of Three Stereoisomeric Forms of2,8-Dimethyl-1,7-dioxaspiro[5.5]undecane, The Main Component of theCephalic Secretion of Andrena Wilkella, Tetrahedron, 1981, 37, 3221; K.Mori and K. Tanida, Synthesis of Three Stereoisomeric Forms of2,8-Dimethyl-1,7-dioxaspiro[5.5]undecane, The Main Component of theCephalic Secretion of Andrena Wilkella, Heterocycles, 1981, 15, 1171; Y.Nakahara et al, Synthetic Studies of Antibiotic A23187 I. ChiralSynthons for C9-C13 and C14-C20, Tetrahedron Lett., 1981, 3197; D. A.Evans et al, Studies Directed Towards the Total Synthesis of theIonophore Antibiotic A-23187, Tetrahedron Lett., 1978, 727; T. M. Crespet al, An Approach to The Synthesis of Ionphores Related to A23187,Tetrahedron Lett., 1978, 3955. Other less general methods for preparing5.5-spiroketals have been reported. See, for example, R. Baker et al,The Chemistry of Spiroketals. Enantispecific Synthesis of the SpiroketalUnits of Avermectins B_(1b) and B_(2b), J. Chem Soc., Chem Commun.,309-11, 1985; Hanessian, et al., Stereocontrolled Synthesis of theSpiroketal Unit of Avermectin B_(1a) Agylone, J. Org. Chem., 1983, 48,pp 4427-30; J. Godoy et al., Synthesis of the Spiroacetal Unit Relatedto the Avermectins and Milbemycins, J. Chem. Soc., Chem. Commun.,1381-82, (1984); P. Kocienski et al., A Synthesis of the SpiroacetalMoiety of Milbemycin β₃, J. Chem. Soc., Chem. Commun., 571-73, (1984);D. R. Williams et al., Synthetic Studies of1,7-dioxaspiro[5.5]undecan-4-ones, Tetrahedron Letters, Vol. 24, No. 5,p 427-30, 1983; P. Kocienski et al., A New Synthesis of1,7-dioxaspiro[5.5]undecanes. Application to a Rectal Gland Secretion ofthe Olive Fruit Fly (Dacus olease), Tetrahedron Letters, Vol. 24, No.36, p 3905-06, 1983; I. T. Kay et al., Spiroketals: The Synthesis of anOlive Fly Pheromone Component, 4-hydroxy-1,7-Dioxaspiro[5.5]undecane,via a Novel Cation-Olefin Cyclisation Step, Tetrahedron Letters, Vol.24, No. 52, p 5915-18, 1983; P. Kocienski et al., A Synthesis ofTalaromycin B, J. Chem. Soc., Chem. Commun., 151-52, 1984.

K. J. Bruza, Studies of Synthetic Methodology Utilizing Cyclic VinylEthers, Ph.D. Thesis, U of Michigan, 1979, describes the preparation of6-oxo-2-methyldecane-1,2,10-triol which cyclizes to a2,7-dioxabicyclo[3.2.1]octane in contrast to the dioxa[5.5]spiroketalsystem of the subject invention.

The diseases or groups of diseases described generally as helminthiasisare due to infection of the animal with parasitic worms known ashelminths. Helminthiasis and helminthosis are prevalent and may lead toserious economic problems in sheep, swine, cattle, goats, dogs, cats,horses, poultry and man. Among the helminths, the groups of worms knownas nematodes, trematodes and cestodes cause widespread and often-timeserious infections in various species of animals including man. The mostcommon genera of nematodes and cestodes infecting the animals referredto above are Dictyocaulus, Haemonchus, Trichostrongylus, Ostertagia,Nematodirus, Cooperia, Bunostomum, Oesophagostomum, Chabertia,Strongyloides, Trichuris, Fasciola, Dicrocoelium, Enterobius, Ascaris,Toxascaris, Toxocara, Ascaridia, Capillaria, Heterakis, Ancylostoma,Uncinaria, Onchocerca, Taenia, Moniezia, Dipylidium, Metastrongylus,Macracanthorhynchus, Hyostrongylus, and Strongylus. Some of thesegeneral attack primarily the intestinal tract while others, inhabit thestomach, lungs, liver and subcutaneous tissues. The parasitic infectionscausing helminthiasis and helminthosis lead to anemia, malnutrition,weakness, weight loss, unthriftiness, severe damage to thegastrointestinal tract wall and, if left to run their course, may resultin death of the infected animals.

DETAILED DESCRIPTION OF THE INVENTION

The anthelmintic spiroketals of this invention are represented byFormula XIX wherein A is --CH, --CH₂ or --CHOP';

wherein P' is C₁ -C₅ alkyl; benzoyl optionally substituted with one, 2or 3 C₁ -C₄ alkyl, C₁ -C₃ alkoxy, halo, C₁ -C₃ alkylthio,trifluoromethyl, nitro; phenyl(C₁ -C₃)alkyl optionally substituted withone, 2 or 3 C₁ -C₄ alkyl, C₁ -C₄ alkoxy, halo, nitro or trifluoromethyl;C₂ -C₆ akoxyalkyl; C₂ -C₆ alkylthioalky; C₁ -C₆ alkanoyl;tetrahydropyranyl; C₁ -C₄ alkyl diphenyl silyl; di(C₁ -C₄ alkyl) phenylsilyl; or tri(C₁ -C₄)alkyl silyl;

wherein . . . is a single bond when A is --CH₂ or --CHOP' and a doublebond when A is --CH;

wherein B is --CR₇ R₈ OR₉ or --R₇ CO;

wherein R₁, R₂, R₄, R₆, R₈, being the same or different, are hydrogen orC₁ -C₅ alkyl;

wherein R₇ is hydrogen, C₁ -C₅ alkyl or C₂ -C₆ alkenyl;

wherein R₃ and R₉, being the same or different, are hydrogen; C₁ -C₅alkyl; benzoyl optionally substituted with one, 2 or 3 C₁ -C₄ alkyl, C₁-C₃ alkoxy, halo, C₁ -C₃ alkylthio, trifluoromethyl, nitro; phenyl(C₁-C₃)alkyl optionally substituted with one, 2 or 3 C₁ -C₄ alkyl, C₁ -C₄alkoxy, halo, nitro or trifluoromethyl; C₂ -C₆ alkoxyalkyl; C₂ -C₆alkylthioalkyl; C₁ -C₆ alkanoyl; tetrahydropyranyl; C₁ -C₄ alkyldiphenyl silyl; di(C₁ -C₄ alkyl) phenyl silyl; or tri(C₁ -C₄)alkylsilyl;

wherein R₅ is hydrogen; C₁ -C₅ alkyl; benzoyl optionally substitutedwith one, 2 or 3 C₁ -C₄ alkyl, C₁ -C₄ alkoxy, halo, C₁ -C₃ alkylthio,trifluoromethyl, nitro; phenyl(C₁ -C₃)alkyl optionally substituted withone, 2 or 3 C₁ -C₄ alkyl, C₁ -C₄ alkoxy, halo, nitro or trifluoromethyl;C₂ -C₆ alkoxyalkyl; C₁ -C₆ alkanoyl; tetrahydropyranyl; C₁ -C₄ alkyldiphenyl silyl; di(C₁ -C₄ alkyl) phenyl silyl; or tri(C₁ -C₄)alkylsilyl; or a mono- or disaccharide.

The synthesis procedure of the present invention is summarized inSchemes A and B. In the various formulas set forth in reaction schemes Aand B, the terms are as defined above, Ar is phenyl substituted at the2-, 2,6- or 2,4,6-positions with C₁ -C₅ alkyl, E is C₁ -C₅ alkyl, M is ametal cation such as an alkali earth metal (for example lithium, sodiumor potassium), X is chlorine or bromine, and P", being the same ordifferent, are C₁ -C₅ alkyl; benzoyl optionally substituted with one, 2or 3 C₁ -C₄ alkyl, C₁ -C₃ alkoxy, halo, C₁ -C₃ alkylthio,trifluoromethyl, nitro; phenyl(C₁ -C₃)alkyl optionally substituted withone, 2 or 3 C₁ -C₄ alkyl, C₁ -C₄ alkoxy, halo, nitro or trifluoromethyl;C₂ -C₆ alkoxyalkyl; C₂ -C₆ alkylthioalkyl; C₁ -C₆ alkanoyl;tetrahydropyranyl; C₁ -C.sub. 4 alkyl diphenyl silyl; di(C₁ -C₄ alkyl)phenyl silyl; or tri(C₁ -C₄)alkyl silyl; or optionally taken together toform a 1,3-dioxolane ring optionally substituted with one or two C₁ -C₅alkyl.

The present invention also encompasses novel compounds obtained as, orreadily derivable from, the various intermediates prepared during thecourse of reaction scheme A and B. Such novel compounds include thespiroketal compounds of Formula XIX and XVII, and the aidol products ofFormula III and III', as well as the compounds of formula V, VI, VII, X,XI, XII, XIV, XV, XVI and XVII.

Certain intermediates of this invention, in particular compounds ofFormula IV, VIII and XVII are useful for the preparation of milbemycinand avermectin macrolides and analogs thereof. See, for example, U.S.Pat. No. 4,408,059, J. Am. Chem. Soc., 104, 4708-10 (1982) and J. Am.Chem. Soc., 104, 4015-4018 (1982).

The present invention is described in further detail with reference toreaction scheme A:

Step 1. The kinetic enolate of ketone II is generated by addition of IIto a solution of a suitable strong base such as lithium diisopropylamideor potassium hexamethyldisilazide. The gegenion of the enolate may beexchanged for certain other metal cations such as zinc, magnesium,titanium, tin, and the like by addition of the corresponding metalhalide. The enolate is generated in a suitably inert solvent such asether, tetrahydrofuran, hexane, toluene, and the like at temperaturesfrom -100° C. to -15° C., preferably -80° C. to -40° C. Subsequentaddition of the aldehyde I at the same temperatures provides the aldolproduct III.

Step 2. Treatment of the aldol product III with aqueous acid in asuitable organic solvent results in hydrolysis of the protecting group Pand the acetonide. Spontaneous intramolecular ketalization yields thespiroketal derivatives IV. Suitable acid catalysts include hydrogenchloride, hydrogen bromide, methane sulfonic acid, sulfuric acid,fluoboric acid, and the like. Preferred is fluoboric acid. Suitableorganic solvents include toluene, tetrahydrofuran, ether, glyme, loweralcohols, and the like. Water concentration may be from 0.1 to 20%,preferably 0.5 to 10% based on volume. Acid concentrations may be from0.05N to 3.0N, preferably 0.1N to 1N, based on total solution volume.

Step 3. The sulfonate ester V is prepared by reaction of IV with asulfonyl chloride, for example p-toluenesulfonyl chloride, in pyridineat -30° C. to +30° C., preferably -15° C. to +10° C.

Step 4. The nitrile VI is obtained from the sulfonate ester V byreaction with an alkali metal cyanide salt, e.g. potassium or sodiumcyanide. The reaction is conducted in a suitable solvent such asacetone, acetonitrile, dimethylformamide or dimethylsulfoxide at 0° to100°; preferably 25° C. to 90° C.

Step 5. Reaction of VI with R₃ X (when R₃ is other than hydrogen) isachieved in a suitable inert solvent, e.g. tetrahydrofuran, toluene,ether, methylene chloride and the like. The reaction is preferablyconducted in the presence of an acid acceptor. Suitable acid acceptorsinclude trialkylamines, pyridines, dimethylaminopyridine, imidazole, andthe like. Reaction can be conducted at -20° to +50°, preferably -10° to+25°.

Step 6. Reduction of the nitrile of VII is conducted with adialkylaluminum hydride, such as diisobutylaluminum hydride, in asuitable inert solvent such as THF, ether, toluene, methylene chlorideor hexane, a -20° C. to 50° C., preferably 10° C. to 30° C. Hydrolysisof the resultant unisolated imine is achieved by mineral acid, e.g.dilute sulfuric acid workup.

Step 7. Condensation of the aldehyde derived in Step VI withtriphenylphosphoranylidene esters IX, where E=lower alkyl of 1-5 C, in asuitable solvent provides the E-α,β unsaturated ester X. Suitablesolvents include methylene chloride, THF, toluene, acetonitrile, ethylacetate and hexane. Reaction temperatures may be from 0° to 100°,preferably 20° to 80°.

Step 8. Reduction of the ester X to the alcohol XI is achieved withhydride reducing agents such as lithium aluminum hydride,diisobutylaluminum hydride, lithium borohydride or borane in suitablyinert solvents such as ether, methylene chloride, THF or toluene, attemperatures from -80° to +50°, preferably -78° C. to 20° C.

Step 9. Oxidation of the primary alcohol XI derived in Step 8 isachieved with known oxidation reagents including pyridiniumchlorochromate, pyridinium dichromate, oxalyl chloride/dimethylsulfoxide and N-chlorosuccinimide/dimethyl sulfoxide, in an appropriatesolvent. Preferred is pyridinium chlorochromate in methylene chloride attemperatures from 0° to 40°, preferably 20° to 40°.

Step 10. Condensation of the aldehyde XII with the hindered aryl estersXIII is achieved under condition similar to Step 1 utilizing the knownprocedure given by C. H. Heathcock, M. C. Pirrang, S. H. Montgomery andJ. Lampe, Tetrahedron, 37, 4087, 1981. The products of this condensationwhen Ar=2,6-dimethylphenyl are shown by nmr to be exclusively threo oranti adducts as defined by C. H. Heathcock, C. T. White, J. J. Morrisonand D. VonDerveer, J. Org. Chem., 46, 1296 (1981).

Step 11. Reaction of the Aldol XIV with R₅ X is achieved similarly tothat of Step 5.

Step 12. Reduction of the ester products of Step 11 is achievedsimilarly to Step 8.

Step 13. Oxidation of the alcohol products of Step 12 is achievedsimilarly to Step 9.

Step 14. Reaction of the aldehyde XVII with organometallic reagents, forexample Grignard reagents, is conducted in suitable solvents such asether or tetrahydrofuran at temperatures from -80° to +30°, preferablyat -20° to +10° C. When R₇ is hydrogen, M' is a suitable reducing agentsuch as sodium borohydride, lithium aluminum hydride and diborane. WhenR₇ is C1-C₅ alkyl, M' is magnesium or lithium.

Step 15. Reaction of the alcohol XVIII with R₈ X is conducted similarlyto Step 5.

The aldehyde I utilized in Step 1 is known: E. J. Corey, H. Shirahama,H. Yamamoto, S. Terashima, A. Venkateswarlu and T. K. Schaaf, J. Amer.Chem. Soc., 93, 1490 (1971).

In Compounds II, II', III and III', P, P', and P" represent a protectinggroup which is stable to the alkaline reaction conditions of Step 1 butis readily hydrolysed under the acidic conditions of Step 2. Suitableprotecting groups include silyl derivatives (preferably silyl ethers,for example t-butyldimethyl, triisopropyl, t-butyldiphenyl silylethers), 2-tetrahydropyranyl ethers, alkoxymethyl ethers (for example,methoxymethyl and 2-methoxyethoxymethyl), alkoxythiomethyl ethers (forexample, methylthiomethylether), benzylethers (for example, benzyl,4-methoxybenzyl and 2,4-dimethoxybenzyl) and the like. The derivativesare readily prepared from the corresponding 1-hydroxy-5-hexanonesaccording to standard procedures.

The 1-hydroxy-5-hexanones are obtained by procedures reported in theliterature, for example, D. R. Williams and B. A. Barner, Tet. Lett.,24, 427 (1983) and N. Lipp Chem. Ber. 18, 3275 (1885).

Alternatively, the hydroxyhexanones may be obtained by mercuric saltcatalysed hydrolysis of the corresponding 1-hydroxy-5-hexynes asdescribed in L. F. Fieser and M. Fieser, Reagents for Organic Synthesis,John Wiley & Sons, N.Y., N.Y., 1967, pp 656-9.

Other oxygen protective groups are set forth in T. W. Greene, ProtectingGroups in Organic Synthesis, Wiley, New York, (1981); J. F. W. McOmie,ed. Protective Groups in Organic Chemistry, Plenum Press (1973); and J.Fuhrop and G. Penzlin, Organic Synthesis, Verlang Chemie (1983).

C means the carbon content of various hydrocarbon-containing moieties isindicated by a prefix designating the minimum and maximum number ofcarbon atoms in the moiety. Thus (C₁ -C₃) alkyl refers to alkyl of oneto 3 carbon atoms, inclusive or methyl, ethyl, propyl, and isopropyl.

Halogen atom (halo) refers to a bromo, chloro, iodo or fluoro atom.

Examples of C₁ -C₄ alkyl are methyl, ethyl, propyl, butyl and isomericforms thereof. Examples of C₁ -C₃ alkoxy are methoxy, ethoxy, propyloxyand isomeric forms thereof. Examples of phenyl(C₁ -C₃)alkyl substitutedwith one, 2 or 3 C₁ -C₄ alkyl, C₁ -C₄ alkoxy, halo or trifluoromethylinclude 4-chlorobenzyl, 2-methylbenzyl, 4-methoxybenzyl,2,4-dimethoxybenzyl or 3,4-dimethoxybenzyl. Examples of C₁ -C₃ alkylthioinclude methylthio, ethylthio and n-propylthio.

Examples of C₂ -C₆ alkoxyalkyl include mono- or dialkoxymethyl, forexample methoxymethyl and 2-methoxyethoxymethyl. Examples of C₂ -C₆alkylthioalkyl, include mono- or dialkylthiomethyl, for example,methylthiomethyl and methoxymethylthiomethyl.

Examples of monosaccharrides include oleandrose, glucose, mannose andthe like. Examples of disaccharides include sucrose, maltose, and lower(2-3) oligomers of olendrose.

Preferred A is CH₂.

Preferred R₁, R₂, R₄ and R₆, being the same or different, are hydrogenor methyl.

Preferred B is --CH₂ OH or CHO.

The following detailed examples of the invention are to be construed asmerely illustrative, and not limitations of the proceeding disclosure inany way whatsoever. Those skilled in the art will promptly recognizeappropriate variations from the procedures both as to reactants as wellas to reaction conditions and techniques.

EXAMPLE 1 Preparation of 6-t-butyldimethylsilyloxyhexan-2-one

A solution of methyl lithium-lithium bromide complex in ether is addeddropwise to a solution of δ-valerolactone (17.2 g, 0.72 mol) intetrahydrofuran (200 ml) cooled in a dry ice-acetone bath. After theaddition, the solution is stirred at -78° for two hours. Water (5 ml) isadded and the mixture allowed to warm to 0°. The mixture is diluted withwater (300 ml) and extracted with ether (4×400 ml). The combinedextracts are dried over sodium sulfate and concentrated under reducedpressure to leave an oil (14.95 g). A portion of this crude mixture (7.4g) is dissolved in DMF (30 ml), imidazole (4.3 g, 64 mmol) andt-butyldimethylsilyl chloride (9.6 g, 64 mmol) are added and the mixturestirred at room temperature overnight. The mixture is diluted with water(100 ml) and extracted with hexane (2×250 ml). The extracts are driedover sodium sulfate and concentrated under reduced pressure to leave anoil (14.92 g). Medium pressure chromatography of this mixture (10% ethylacetate/hexane) on silica gel yields the title compound (9.65 g, 49%based on valerolacetone) as an oil.

Anal.: Calc'd for C₁₂ H₂₆ O₂ Si: C, 62.55; H, 11.37. Found: C, 61.63; H,11.38.

PMR (CDCl₃): 0.07, 0.93, 1.61, 2.17, 2.49, 3.65 ppm.

EXAMPLE 2 Preparation of8-t-butylidimethylsilyloxy-1-(2,2-dimethyl-1,3-dioxolan-4-yl)-2-hydroxyoctan-4-one

A solution of n-butyl lithium in hexane (119 ml, 1.6M, 0.19 mol) isadded dropwise to a solution of diisopropylamine (19.3 g, 0.19 mol) inTHF (100 ml) cooled in an ice bath. After the addition, the mixture isstirred for 20 minutes then cooled to -78°. A solution of6-t-butyldimethylsilyloxy-hexan-2-one (40.0 g, 0.174 mol) in THF isadded dropwise. The resultant mixture is stirred for 90 minutes then asolution of 2,2-dimethyl-1,3-dioxolane-4-acetaldehyde (25.1 g, 0.174mol) in THF (100 ml) is added dropwise. After the addition, the mixtureis stirred for 2 hours, then water (10 ml) slowly added. The mixture iswarmed to 0°, diluted with water (300 ml) and extracted with ether(2×500 ml). The extracts are washed with saturated brine, dried oversodium sulfate and concentrated under reduced pressure to leave thecrude product (63.5 g) an oil. A portion of this material (46 g) ischromatographed on silica gel (2.5 Kg) eluting with 25% ethylacetate/hexane to give the title compound,8-t-butyldimethylsilyloxy-1-(2,2-dimethyl-1,3-doxolan-4-yl)-2-hydroxyoctan-4-one;(23 g, 49%) an oil.

Anal.: Calc'd for C₁₉ H₃₈ O₅ Si: C, 60.92; H, 10.23. Found: C, 61.50; H,10.49.

PMR (CDCl₃): 0.11, 0.95, 1.41, 1.46, 2.57, 3.57, 4.24 ppm.

EXAMPLE 3 Preparation of4-R,S-hydroxy-2-S,R-hydroxymethyl-6-R,S-1,7-dioxaspiro[5.5]undecane

Fluoboric acid (5 ml, 50%) is added at room temperature to a solution of8-t-butyldimethylsilyloxy-1-(2,2-dimethyl-1,3-dioxolan-4-yl)-2-hydroxyoctan-4-one(25.0 g, 66.7 mmol) in ether (150 ml). The mixture is stirred at roomtemperature for 30 minutes during which time a precipitate forms. Theprecipitate is filtered to give the title compound (6.05 g, 44.8%) as asolid, m.p. 121°-2°. Tlc of this material (90% ethyl acetate/hexane)showed only trace of impurities. Two additional crops of the titlecompound (0.48 g and 0.42 g) are obtained by concentration andtrituration with ether/pentane. Other stereoisomers are obtained and canbe isolated by silica gel chromatography. An analytical sample of thetitle compound is recrystallized from acetonitrile, mp 156°-8°.

Anal.: Calc'd for C₁₀ H₁₈ O₈ : C, 59.37; H, 8.97 Found: C, 59.21; H,9,15.

PMR (CDCl₃): 1.54, 3.48, 3.86 ppm.

The mass spectra shows m/e 202 (M+).

EXAMPLE 4 Preparation of4-hydroxy-2-[[(4-methylphenylsulfonyl)oxy]methyl]-1,7-dioxaspiro[5.5]undecane

To a stirred suspension of the spiroketal diol,4-R,S-hydroxy-2-S,R-hydroxymethyl-6-R,S-1,7-dioxaspiro[5.5]undecane,(35.00 g; 173 mmoles) in dry pyridine (175 ml) at -15° under a nitrogenatmosphere is added solid tosyl chloride (34.64 g; 182 mmoles) in asingle portion. The reaction mixture is stirred at -10° to -15° for 60minutes, allowed to warm to room temperature then stirred for another 60minutes. The reaction mixture is poured into ice water (250 ml) andextracted with ether (2×250 ml). The organic phases are combined, washedwith 2N HCl (3×100 ml), saturated sodium bicarbonate, then dried overanhydrous magnesium sulfate. Concentration in vacuo yields the titlecompound,4-hydroxy-2-[[(4-methylphenylsulfonyl)oxy]methyl]-1,7-dioxaspiro[5.5]undecane;(45.4 g: 73.6%) as an oil.

PMR (CDCl₃): 1.55, 2.47, 3.46, 4.01, 7.34, 7.77 ppm.

EXAMPLE 5 Preparation of4-hydroxy-1,7-dioxaspiro[5.5]undecaneacetonitrile

A mixture of the tosylate,4-hydroxy-2-[[(4-methylphenylsulfonyl)oxy]methyl]-1,7-dioxaspiro[5.5]undecane,(87.9 g; 247 mmoles), potassium cyanide (19.3 g; 296 mmoles) anddimethylsulfoxide (300 ml) is heated at 80°-90° for 150 minutes withstirring under a nitrogen atmosphere. After cooling to 25°, the reactionmixture is diluted with ether (1500 ml) and mixed thoroughly. Thesupernatant is decanted and the extraction process repeated. Thecombined decantates are washed with saturated sodium chloride and driedover anhydrous magnesium sulfate. Concentration in vacuo gives an oilwhich is chromatographed (30% ethyl acetate/hexane) to afford the titlecompound, 4-hydroxy-1,7-dioxaspiro[5.5]undecaneacetonitrile; (28.4 g;54.7%) as an oil.

PMR (CDCl₃): 1.70, 2.47, 3.55, 3.93 ppm.

EXAMPLE 6 Preparation of4-[(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]undecaneacetonitrile

To a mixture of imidazole (9.15 g; 134 mmoles) and4-hydroxy-1,7-dioxaspiro[5.5]undecaneacetonitrile, (28.4 g; 134 mmoles)in DMF (135 ml) at 0° us added tert-butyldimethylchlorosilane (20.3 g;134 mmoles). The cooling bath is removed, and the reaction mixtureallowed to stir at ambient temperature for 6 hours. The reaction mixtureis poured into water (900 ml) and extracted with hexane (2×300 ml). Theextracts are combined, dried over anhydrous sodium sulfate andconcentrated in vacuo to afford the title compound,4-[(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]undecaneacetonitrile;(39.2 g; 89.5%) as an oil. Chromatography (10% ethyl acetate/hexane)provided an analytical sample.

Anal.: Calc'd for: C₁₇ H₃₁ NO₃ Si: 62.73; H, 9.60; N, 4.30. Found: C,62.41; H, 9.63; N, 4.03.

PMR (CDCl₃): 0.19, 0.99, 1.69, 2.60, 3.65, 4.07 ppm.

EXAMPLE 7 Preparation of4-[(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]undecaneacetaldehyde

To a solution of4-[(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]undecaneacetonitrile,(37.0 g; 114 mmoles) in methylene chloride (400 ml) at 25° is addeddropwise a solution of 1M DIBAL in methylene chloride (114 ml; 114mmoles). The reaction is moderately exothermic. After ninety minutesmethanol (15 ml) is cautiously added dropwise (foaming). After tenminutes the reaction mixture is poured into a mixture of 6.67N sulfuricacid (200 ml) and crushed ice (400 g). The mixture is intermittentlyshaken over a period of ten minutes. The organic phase is separated,washed with saturated sodium chloride, dried over anhydrous magnesiumsulfate, and concentrated in vacuo to afford the title compound,4-[(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]undecaneacetaldehyde;(34.2 g; 91.7%) as an oil.

PMR (CDCl₃): 0.15, 0.97, 1.64, 2.61, 3.64, 4.18, 9.91 ppm.

EXAMPLE 8 Preparation of ethyl4-[[4-(1,1-dimethylethyl)silyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-2-methyl-2E-butenoate

A mixture of (carbethoxyethylidene)triphenylphosphorane (41.3 g; 114mmoles) and4-[(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]undecaneacetaldehyde,(34.2 g; 104 mmoles) in acetonitrile (400 ml) is refluxed under anatmosphere of nitrogen with stirring for two hours. The mixture isconcentrated in vacuo and the residue chromatographed (10% ethylacetate/hexane) to give the title compound, ethyl4-[[4-(1,1-dimethylethyl)silyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-2-methyl-2E-butenoate;(32.1 g; 68.3%) as a clear, yellow oil.

Anal. Calc'd for: C₂₂ H₄₀ O₅ Si: C, 6404; H, 9.77 Found: C, 64.46; H,10.26.

PMR (CDCl₃): 0.15, 0.96, 1.36, 1.66, 1.95, 2.45, 3.61, 3.91, 4.26, 6.97ppm.

EXAMPLE 9 Preparation of4-[[4-(1,1-dimethylethyl)silyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-2-methyl-2E-butenol

A solution of 1M DIBAL (155 ml; 155 mmoles) is added dropwise to asolution of ethyl4-[[4-(1,1-dimethylethyl)silyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-2-methyl-2E-butenoate,(29.0 g; 70.3 mmoles) in methylene chloride (350 ml) with stirring undernitrogen at -78°. Upon completion of the addition, the reaction mixtureis allowed to warm to 2° and stirred for two hours. The reaction mixtureis cooled to 0° and treated dropwise (slight foaming) with methanol (45ml). After 15 minutes the reaction mixture is partitioned betweenmethylene chloride (500 ml) and a mixture of 6.67N sulfuric acid (150ml) and crushed ice (300 g). The mixture is intermittently shaken over aten minute period. The layers are separated and the aqueous phaseextracted with methylene chloride (500 ml). The combined organic phasesare dried over anhydrous sodium sulfate, filtered through celite, andconcentrated in vacuo to give an oil. Chromatography (15-40% ethylacetate/hexane) yields the title compound,4-[[4-(1,1-dimethylethyl)silyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-2-methyl-2E-butenol;(21.8 g; 83.8%) as an oil.

Anal.: Calc'd for: C₂₀ H₃₈ O₄ Si: C, 64.82; H, 10.34. Found: C, 64.65;H, 10.30.

PMR (CDCl₃): 0.15, 0.97, 1.64, 1.78, 2.34, 3.61, 4.10, 5.59 ppm.

EXAMPLE 10 Preparation of4-[[4-(1,1-dimethylethyl)silyl]-oxy-1,7-dioxaspiro[5.5]undec-2-yl]-2-methyl-2E-butanealdehyde

To a solution of ethyl4-[[4-(1,1-dimethylethyl)silyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-2-methyl-2E-butenoate,(10.0 g; 27.0 mmoles) in methylene chloride (160 ml) is added finallypowdered pyridinium chlorochromate (PCC; 8.7 g; 40.5 mmoles) in a singleportion with stirring under nitrogen at 25°. After twenty minutes thereaction mixture is diluted with ether (800 ml) and filtered throughcelite. The chromium salt residue is washed several times with ether,the washes filtered through celite, and the combined filtrates reducedin volume to 100 ml, filtered through silica gel and concentrated invacuo to an oil. Chromatography (7.5% ethyl acetate/hexane yields thetitle compound,4-[[4-(1,1-dimethylethyl)silyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-2-methyl-2E-butanealdehyde;(5.42 g; 54.5%0 as an oil).

PMR (CDCl₃): 0.16, 0.97, 1.77, 2.63, 3.59, 4.15, 6.70, 9.51 ppm.

EXAMPLE 11 Preparation of 2,6-dimethylphenyl2,4-dimethyl-6-[[4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-3-hydroxy-4E-hexenoate

To a solution of diisopropylamine (1.0 ml; 7/08 mmoles) in THF (15 ml)at 0° under nitrogen is added dropwise a solution of 1.6M n-butyllithium in hexane (4.4 ml; 7.08 mmoles). After fifteen minutes thereaction mixture is cooled to -78° and a solution of 1,6-dimthylphenylpropionate (1.26 g; 7.08 mmoles) in THF (10 ml) added dropwise. After 60minutes, a solution of4-[[4-(1,1-dimethylethyl)silyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-2-methyl-2E-butanealdehyde,(2.61 g; 7.08 mmoles) in THF (10 ml) is added dropwise. After tenminutes the reaction is quenched by the rapid addition of saturatedammonium chloride solution (2.5 ml) then allowed to warm to 0°. Themixture is diluted with water (100 ml) and extracted with ether (2×100ml). The organic phases are combined, washed with 1% hydrochloric acidand then dried over anhydrous magnesium sulfate. Concentration in vacuogives an oil which is chromatographed (10% ethyl acetate/hexane) toyield the title compound, 2,6-dimethylphenyl2,4-dimethyl-6-[[4-(1,1-dimethylethyl)dimethylsily]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-3-hydroxy-4E-hexenoate;(1.82 g; 47%) as a semi-solid.

Anal.: Calc'd for C₃₁ H₅₀₅ Si: C, 68.09; H, 9.22. Found: C, 67.75; H,9.26.

PMR (CDCl₃): 0.16, 0.98, 1.33, 1.73, 2.28, 2.38, 3,05, 3.63, 4.12, 4.37,5.70, 7.12 ppm.

EXAMPLE 12 Preparation of 2,6-dimethylphenyl2,4-dimethyl-6-[[(4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-3-(methoxymethyl)oxy-4E-hexenoate

To a solution of2,6-dimethylphenyl2,4-dimethyl-6-[[4-(1,1-dimethyl-ethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]undec-2-yl]-3-hydroxy-4E-hexenoate,(1.66 g; 3.04 mmoles) and diisopropylethylamine (1.16 ml; 6.68 mmoles)in methylene chloride (5 ml) at 0° is added chloromethylmethyl ether(0.46 ml; 6.08 mmoles). The ice bath is removed and the reaction mixtureallowed to stir at ambient temperature under nitrogen for 30 hours. Thereaction mixture is diluted with water (10 ml) and extracted with ether(2×25 ml). The organic phases are combined, washed with water, saturatedsodium chloride solution, then dried over anhydrous magnesium sulfate.Concentration in vacuo gives an oil which is chromatographed (10% ethylacetate/hexane) to yield the title compound, 2,6-dimethylphenyl2,4-dimethyl-6-[[(4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-3-(methoxymethyl)oxy-4E-hexenoate;(1.49 g; 82.8%) as an oil. The pmr spectrum shows H₁₃ as a doublet, J=10.5 Hz, centered at 4.40 ppm indicating anti-isomers. The methylene ofthe methoxymethyl group appears as a pair of AB quartets. The higherfield absorbing proton isomers overlap and display a broad doublet at4.55 ppm while the lower field protons appear as a quartet centered at4.73 ppm . Based on the relative peak heights of this quartet the ratioof α and β anti-isomers is 55:45.

Anal.: Calc'd for C₃₃ H₅₄ O₇ Si: C, 67.08; H, 9.21. Found: C, 67.19; H,9.64.

PMR (CDCl₃): 0.17, 0.98, 1.27, 1.74, 1.82, 2.30, 2.41, 3.11, 3.37, 3.64,4.07, 4.33, 4.62, 5.74, 7.13 ppm.

EXAMPLE 13 Preparation of2,4-dimethyl-6-[[(4-(1,1-dimethylethyl)dimethylsilyl]-oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-3-(methoxymethyl)oxy-4E-hexen-1-ol,Compound No. 13

To a solution of 2,6-dimethylphenyl2,4-dimethyl-6-[[(4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-3-(methoxymethyl)oxy-4E-hexenoate,(3.30 g; 5.58 mmoles ) in methylene chloride (100 ml) at -78° undernitrogen is added dropwise in 1N solution of DIBAL in methylene chloride(13.4 ml; 13.4 mmoles). After 30 minutes the reaction mixture is treateddropwise with methanol (5.0 ml) and then allowed to warm to 0°. Themixture is partitioned between methylene chloride (250 ml) and ice cold2N sulfuric acid (150 ml) and intermittently shaken over a ten minuteperiod. The organic phase is dried over anhydrous magnesium sulfate,concentrated in vacuo, and chromatographed (20% ethyl acetate/hexane) togive the title compound,2,4-dimethyl-6-[[(4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-3-(methoxymethyl)oxy-4E-hexen-1-ol.

Anal.: Calc'd for C₂₅ H₄₈ O₆ Si: C, 63.52; H, 10.23. Found: C, 63.31; H,10.15.

PMR (CDCl₃): 0.15, 0.76, 0.96, 1.62, 1.67, 2.36, 3.47, 3.72, 3.88, 4.16,4.60, 5.56 ppm.

EXAMPLE 14 Preparation of2,4-dimethyl-6-[[(4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-3-(methoxymethyl)oxy-4E-hexenaldehyde,Compound No. 14

To a solution of Preparation of2,4-dimethyl-6-[[(4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]3-(methoxymethyl)oxy-4E-hexen-1-ol,(404 mg; 0.855 mmoles) in methylene chloride (5 ml) is added finelypowdered pyridinium chlorochromate (550 mg; 2.56 mmoles) in a singleportion with stirring under nitrogen at 25°. After four hours thereaction mixture is diluted with ether (20 ml), stirred five minutes andfiltered through silica gel. The filtrate is concentrated in vacuo to anoil which is chromatographed (10% ethyl acetate/hexane) to yield thetitle compound,2,4-dimethyl-6-[[(4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-3-(methoxymethyl)oxy-4E-hexenaldehyde;(317 mg; 79%) as an oil.

Anal.: Calc'd for C₂₅ H₄₆ O₆ Si: C, 63.79; H, 9.85. Found: C, 63.93; H,9.77

NMR (CDCl₃): 0.15, 0.98, 1.06, 1.64, 1.71, 2.40, 3.43, 3.64, 4.01, 4.23,4.63, 9.96 ppm.

EXAMPLE 15 Preparation of3,5-dimethyl-1-[[(4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-4-(methoxymethyl)oxyocta-2E,7-diene-6-ol

To a solution of 1M vinylmagnesium bromide in ether (3.0 ml; 3.0 mmoles)at 0° under nitrogen is added THF (2.5 ml) followed by dropwise additionof a solution of aldehyde 3; (1.00 g; 2.12 mmoles) in ether (20 ml).Upon completion of addition the ice bath is removed and the reactionmixture stirred at ambient temperature for five hours. The reactionmixture is diluted with ether (125 ml), washed in turn with saturatedammonium chloride solution and saturated sodium chloride solution andthe organic phase dried over anhydrous magnesium sulfate. Concentrationin vacuo gives an oil. Chromatography (15% ethyl acetate/hexane) affords16 (611 mg; 57.6%) as an oil.

PMR (CDCl₃): 0.15, 0.83, 0.98, 1.69, 2.38, 3.08, 3.50, 3.64, 4.04, 4.57,4.74, 5.24, 5.36, 5.50, 5.64, 5.70, 5.97, and 6.18.

The spiroketals of Formula XIX can be used as the pure compounds or asmixtures of pure compounds but for practical reasons the compounds arepreferably formulated as anthelmintic compositions and administered as asingle or multiple dose, alone or in combination with otheranthelmintics (e.g. avermectins, benzimidazoles, levamisole,praziquantel, etc.). For example, aqueous or oil suspensions can beadministered orally, or the compounds can be formulated with a solidcarrier for feeding. Furthermore, an oil suspension can be convertedinto an aqueous emulsion by mixing with water and injecting the emulsionintramuscularly, subcutaneously or into the peritoneal cavity.

Pure compounds, mixtures of the active compounds, or combinationsthereof with a solid carrier can be administered in the animal's food,or administered in the form of tablets, pills, boluses, wafers, pastes,and other conventional unit dosage forms, as well as sustained releasedosage forms which deliver the active compound over an extended periodof days, weeks or months. All of these various forms of the activecompounds of this invention can be prepared using physiologicallyacceptable carriers and known methods of formulation and manufacture.

Representative solid carriers conveniently available and satisfactoryfor physiologically acceptable, unit dosage formulations include cornstarch, powdered lactose, powdered sucrose, talc, stearic acid,magnesium stearate, finely divided bentonite, and the like. The activeagent can be mixed with a carrier in varying proportions from, forexample, about 0.001 percent by weight in animal feed to about 90 or 95percent or more in a pill or capsule. In the latter form, one might useno more carrier than sufficient to bind the particles of activecompound.

In general, the compounds can be formulated in stable powders orgranules for mixing in an amount of feed for a single feeding or enoughfeed for one day and thus obtain therapeutic efficacy withoutcomplication. It is the prepared and stored feeds or feed premixes thatrequire care. A recommended practice is to coat a granular formulationto protect and preserve the active ingredient. A prepared hog-feedcontaining about 0.2 percent of the active compound will provide adosage of about 100 mg per kg body weight for each 100 lb pig in itsdaily ration.

A solid diluent carrier need not be a homogeneous entity, but mixturesof different diluent carriers can include small proportions of adjuvantssuch as water; alcohols; protein solutions and suspensions like skimmedmilk; edible oils; solutions, e.g., syrups; and organic adjuvants suchas propylene glycols, sorbitol, glycerol, diethyl carbonate, and thelike.

The solid carrier formulations of the inventions are convenientlyprepared in unit dosage forms, to facilitate administration to animals.Accordingly, several large boluses (about 20 g weight) amounting toabout 54 g of active compound would be required for a single dosage to a900 lb horse at a dosage rate of 50 mg/kg of body weight. Similarly, a60 lb lamb at a dosage rate of 100 mg/kg of body weight would require apill, capsule, or bolus containing about 2.7 g of active compound. Asmall dog, on the other hand, weighing about 20 lbs. would require atotal dosage of about 225 mg at a dosage rate of 25 mg/kg of bodyweight. The solid, unit dosage forms can be conveniently prepared invarious sizes and concentrations of active ingredient, to accommodatetreatment of the various sizes of animals that are parasitized by worms.

Liquid formulations can also be used. Representative liquid formulationsinclude aqueous (including isotonic saline) suspensions, oil solutionsand suspensions, and oil in water emulsions. Aqueous suspensions areobtained by dispersing the active compound in water, preferablyincluding a suitable surface-active dispersing agent such as cationic,anionic, or non-ionic surface-active agents. Representative suitableones are polyoxyalkylene derivatives of fatty alcohols and of sorbitanesters, and glycerol and sorbitan esters of fatty acids. Variousdispersing or suspending agents can be included and representative onesare synthetic and natural gums, tragacanth, acacia, alginate, dextran,gelatin, sodium carboxymethylcellulose, methylcellulose, sodiumpolyvinylpyrrolidone, and the like. The proportion of the activecompound in the aqueous suspensions of the invention can vary from about1 percent to about 20 percent or more.

Oil solutions are prepared by mixing the active compound and an oil,e.g. an edible oil such as cottonseed oil, peanut oil, coconut oil,modified soybean oil, and sesame oil. Usually, solubility in oil will belimited and oil suspensions can be prepared by mixing additional finelydivided compound in the oil.

Oil in water emulsions are prepared by mixing and dispersing an oilsolution or suspension of the active compound in water preferably aidedby surface-active agents and dispersing or suspending agents asindicated above.

In general, the formulations of this invention are administered toanimals so as to achieve therapeutic or prophylactic levels of theactive compound. In this regard, it should be noted that theconcentration of active compound in the formulation selected foradministration is in many situations not critical. One can administer alarger quantity of a formulation having a relatively low concentrationand achieve the same therapeutic or prophylactic dosage as a relativelysmall quantity of a relatively more concentrated formulation. Morefrequent small dosages will likewise give results comparable to onelarge dose. One can also administer a sustained release dosage system(protracted delivery formulation) so as to provide therapeutic and/orprophylactic dosage amounts over an extended period. Unit dosage formsin accordance with this invention can have anywhere from less than 1 mgto 500 g of active compound per unit.

Although the anthelmintic agents of this invention will find theirprimary use in the treatment and/or prevention of helminth parasitismsin domesticated animals such as sheep, cattle, horses, dogs, swine,goats and poultry, they are also effective in treatment that occurs inother warm blooded animals including man. The optimum amount to beemployed for best results will, of course, depend upon the particularspiroketal compound employed, species of animal to be treated, theregimen treatment and the type and severity of helminth infection.Compounds of Formula XIX can be administered by the oral or parenteralroute of administration at a dose of about 0.2 to 200 mg/kg of animalbodyweight (such total dose being given at one time, in a protractedmanner or in divided doses over a short period of time such as 1-4days). The technique for administering these materials to animals areknown to those skilled in the veterinary and medical fields.

2,4-Dimethyl-6-[[4-(1,1-dimethylethyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-3-(methoxmethyl)oxy-4E-hexen-1ol,Compound No. 13, and2,4-dimethyl-6-[[(1,1-dimethyletheyl)dimethylsilyl]oxy-1,7-dioxaspiro[5.5]-undec-2-yl]-3-(methoxymethyl)oxy-4E-hexenaldehyde,Compound No. 14, have demonstrated a minimum effective concentration of2 ppm and 20 ppm, respectively, against the free living nematodeCaenorhabditis elegans in accordance with Procedure 1.

Compounds No. 13 and 14 have also been tested at 600 mg/kg against S.obvelata and N. dubius in mice in accordance with Procedure No. 2 anddemonstrated activity as set forth in Table I.

                  TABLE I                                                         ______________________________________                                                      % Clearance                                                                   S. obvelata                                                                           N. dubius                                               ______________________________________                                        Compound #14    40%       80%                                                 Compound #13    20-100%   25-40%                                              ______________________________________                                    

In a trial in sheep, in accordance with Procedure 3, at oral doses of 2and 20 mg/kg, no activity against H. contortus was observed withCompound No. 13. However, at higher dosages and/or against other wormsanthelmintic activity is anticipated.

In trial in sheep, in accordance with Procedure 3, at oral doses of 2and 14.4 mg/kg, 24% and 30% clearance, respectively, against H.contortus was observed with Compound No. 14.

DEFINITIONS

The definitions and explanations below are for the terms as usedthroughout the entire patent application including both thespecification and claims.

All temperatures are in degrees Celsius.

TLC refers to thin-layer chromatography.

Brine refers to an aqueous saturated sodium chloride solution.

When solvent pairs are used, the ratio of solvents used arevolume/volume (v/v).

DIBAL refers to diisobutylaluminum hydride.

DMF refers to dimethylformamide.

THF refers to tetrahydrofuran.

PMR refers to proton magnetic resonance spectroscopy, chemical shiftsare reported in ppm (δ) downfield from TMS.

TMS refers to tetramethylsilane.

Procedure 1

Materials and Methods: Media Preparation--Nematode Growth Agar (NGA)Plates--3 g NaCl, 2.5 g Bactopeptone, and 17 g Bactoagar are mixed in975 ml of distilled water plus 1 ml of a 5 mg/ml solution ofchloresterol in ethanol. The resulting mixture is autoclaved at 120° for20 minutes, and then 1 ml 1M CaCl₂, 1 ml 1M MgSO₄, and 25 ml 1M KH₂ PO₄(pH 6.0), each sterile filtered, are added to the mixture. Immediatelythereafter 15 ml quantities are plated aspetically into 100×20 mmplastic petri dishes (tissue culture grade). NGA plates are stored at 4°C. until needed.

Nematode Washing Buffer (M9 buffer)--6 g Na₂ HPO₄, 5 g NaCl, and 0.25 gMgSO₄.7H₂ O are mixed in 1 liter of distilled water. Suitable volumes(50, 90, and 450 ml) are dispensed into Erlenmeyer flasks and autoclavedfor 20 minutes at 120°. M9 buffer is stored at 4° C. until needed.

Escherichia coli Streak-Plates--8 g NaCl, 10 g Bactotryptone, 5 g yeastextracts, 15 g agar, and 5 mg thymidine are added to 500 ml of distilledwater and mixed well, after which the volume is brought to 1 liter withdistilled water. The mixture is autoclaved at 120° C. for 20 minutes,and then 15 ml quantities are plated aseptically into 100×20 mm plasticpetri dishes (tissue culture grade). These plates are stored at 4° C.until needed.

Escherichia coli broth--The same ingredients are used as for E. colistreak-plates except the agar is omitted and 10 mg cysteine is added.Aliquots of 10 ml are dispensed into disposable scintillation vials andthe lightly capped vials are autoclaved for 20 minutes at 120° C. Theseare stored at 4° C. until needed.

Maintenance of C. elegans--A culture of C. elegans is maintained at 20°C. on NGA plates seeded with an uracil-requiring mutant of Escherichiacoli. A few nematodes (any stage) are aseptically transferred to freshNGA plates weekly; separate NGA plates from each transfer are used thefollowing week for screening trials and for subsequent transfers. Oneweek prior to C. elegans transfers, NGA plates are seeded asepticallywhen 1 ml of broth containing a 4-day-old growth of E. coli which isspread evenly across the plate to produce an E. coli lawn. The E. colimutant required for maintenance of C. elegans also is transferredaseptically to fresh streak-plates weekly; separate streak-plates areused to inoculate broth tubes (for use in screening trials or to seedNGA plates) at 3 days posttransfer or to inoculate fresh streak-plates,one week after transfer. Escherichia coli streak-plates, E. coli brothtubes, and NGA plates seeded with E. coli are maintained at roomtemperature (20°-23° C.).

Screening Trials--The test medium is prepared on the day a screeningtrial is to be initiated and consists of 9 parts M9 buffer and 1 part E.coli broth containing well grown (3-4 days) E. coli. In addition,ampicillin (50 μg/ml) and nystatin (100 U/ml) are added to the testmedium which is then allowed to stand at room temperature for 2 hours.During the 2-hour waiting period all test substances (10 and 30 mgquantities) are dissolved in 1 ml of DMSO. Following the waiting period,the test medium is dispensed, 2 ml per well, into Sterilin Repli Dishes(square, 25-well covered dishes). Each well then receives 10 μl of atest substance (23 wells per dish) or 10 μl of a standard (1 well perdish) or is used as a nontreated control (1 well per dish). Thisprovides "in well" effective concentrations of 50 and 150 ppm for eachtest substance. Once all wells have been charged, 20-25C. elegans (allstages of development) are added to each well in a drop of M9 buffer.The worm suspension is prepared immediately prior to use by rinsing a1-week-old C. elegans culture into an Erlenmeyer flask containing M9buffer; this suspension is then diluted with M9 buffer until the desired20-25 worms per drop concentration is reached. Following the addition ofC. elegans to each well, the plates are incubated for 1 week at 20° C.in the dark.

Readings of Screening Trial Results--Readings are made with a dissectingmicroscope on each well after both 3 and 7 days of incubation. Thenontreated and standard wells are read first to determine that all is inorder for each dish. Nontreated wells should show a significant increasein worm numbers (up to 50-fold,) while a standard treatment shouldcontain no or very few live worms. Test substances are scored basedprimarily on worm numbers, although appearance, movement, anddevelopmental stages present also can influence scoring.

The results are reported as minimum effective concentration (mec) asdefined by K. G. Simpkin and G. C. Coles, J. Chem. Tech. Biotechnol. 31,p 66, 1981.

Procedure 2

Mice are infected with S. obvelata and N. dubius. Fresh caecal contentscontaining S. obvelata are mixed with corn meal and fed to mice whichhad been starved for 24 hours. The mice are then placed into communitycages with other mice known to have patent infections of S. obvelata andmonitored until high levels of infection are observed at necropsy inrandomly selected indicator animals. Each mouse is then given ˜100infective larvae of N. dubius per os. Two weeks later mice from eachcommunity cage are sacrificed and examined for both helminth species.Following sampling, the remaining animals are randomly allotted totreated groups of five mice/group. Throughout the experiments micereceive food and water ad lib.

Test compounds are evaluated orally in five mouse groups at 600 mg/kg.Oral treatments are administered with a 1 cc tuberculin syringe fittedwith a cannula. Each mouse receives 1/4 of the test dose/day on fourconsecutive days in 0.1 ml of vehicle (40% glycerol formal, 5%polyvinylpyrrolidone C-15 in propylene glycol). In each separateexperiment ten mice are used as non-treated controls.

All mice in each trial are sacrificed three days after the lasttreatment and examined for N. dubius and S. obvelata. The clearance rateis calculated according to the following formula: ##EQU1##

Procedure 3

In individual experiments all sheep are treated identically, howevernon-critical variations occur between experiments. All of the sheep usedin this procedure are treated twice with levamisole hydrochloride orallyat 8 mg/kg or once each with ivermectin parenterally at 200 μg/kg andlevamisole hydrochloride orally at 8 mg/kg. The second treatment in eachcase is administered 4-7 days after the first treatment. Two weeks afterthe second treatment all sheep are inoculated per os with -3,500 to-7,500 infective larvae of H. contortus. Rectal fecal samples are takenfrom each sheep 26-41 days post-inoculation (PI), and these samples areexamined for eggs of H. contortus using the McMaster counting chambertechnique. All sheep harboring good infections of H. contortus arerandomly allocated to a treatment group; those which do not exhibitsuitable infections are dropped from the study. One to three days lateron days 27-42 PI each sheep remaining in the study (excluding thenon-treated controls) is treated with a test compound (orally orparenterally at 100 mg/kg unless indicated otherwise) or a standard(levamisole hydrochloride orally at 8 mg/kg) or is used as an untreatedcontrol. All sheep received food and water ad lib. throughout theexperiment.

Prior to administration, all solid compounds are finely ground using amortar and pestle. Oral compounds are suspended in 20-30 ml of sterilevehicle #98 (each ml contains: carboxymethylcellulose--10 mg,polysorbate80-4 mg, propylparaben--0.42 mg) using a sonicator andadministered along with a tap water wash via a stomach tube. Theparenteral compounds are similarly suspended in 20-30 ml of the sterilevehicle and given by intraperitoneal injection using a 13 gauge, 2 inchneedle and a 50 ml syringe. All test compounds are given to a singlesheep/route of administration. Two or more sheep are treated withlevamisole hydrochloride and five are used as non-treated controls. Allanimals are monitored for signs of toxicity following treatment.

The sheep are sacrificed 7-12 days after treatment (days 35-49 PI), andthe abomasum is ligated and removed from each sheep. Each abomasum islongitudinaly sectioned and rinsed into an 80 mesh sieve. Sieve contentsare collected in individual containers and fixed in formol-alcohol.Later each sample is transferred to a 1000 or 2000 ml beaker and thevolume brought to 400-1000 ml with tap water. The total number of wormsin a 40-100 ml aliquot (10%) is determined. When no worms are found inthe 10% aliquot, the entire sample is examined. Total worm number/sheepand percentage clearance for each treatment are calculated. Percentageclearance for a particular test compound in a given trial is determinedaccording to the following formula: ##EQU2##

Sheep which die within 24 hr following treatment are not examined forworms, while any that die between 24 hr post-treatment and necropsy areexamined in an identical manner as that described above. ##STR1##

I claim:
 1. A method of killing helminths in animals which comprisesadministerng to an animal a therapeutic dosage of a spiroketal of theformula:wherein A is --CH, or --CH₂ ; wherein . . . is a single bondwhen A is --CH₂ and a double bond when A is --CH; wherein B is --CR₇ R₈OR₉ or --CHO; wherein R₁, R₂, R₄, R₆, and R₈, being the same ordifferent, are hydrogen or C₁ -C₅ alkyl; wherein R₇ is hydrogen, C₁ -C₅alkyl or C₂ -C₆ alkenyl; wherein R₃ is C₁ -C₅ alkyl; benzoyl optionallysubstituted with one, 2 or 3 C₁ -C₄ alkyl, C₁ -C₃ alkoxy, halo, C₁ -C₃alkylthio, trifluoromethyl, nitro; phenyl(C₁ -C₃)alkyl optionallysubstituted with one, 2 or 3 C₁ -C₄ alkyl, C₁ -C₄ alkoxy, halo, nitro ortrifluoromethyl; C₂ -C₆ alkoxyalkyl; C₂ -C₆ alkylthioalkyl; C₁ -C₆alkanoyl; tetrahydropyranyl; C₁ -C₄ alkyl diphenyl silyl; di(C₁ -C₄alkyl) phenyl silyl; or tri(C₁ -C₄)alkyl silyl; wherein R₅ is hydrogen;C₁ -C₅ alkyl; benzoyl optionally substituted with one, 2 or 3 C₁ -C₄alkyl, C₁ -C₃ alkoxy, halo, C₁ -C₃ alkylthio, trifluoromethyl, nitro;phenyl(C₁ -C₃)alkyl optionally substituted with one, 2 or 3 C₁ -C₄alkyl, C₁ -C₄ alkoxy, halo, nitro or trifluoromethyl; C₂ -C₆alkoxyalkyl; C₁ -C₆ alkanoyl; tetrahydropyran; C₁ -C₄ alkyl diphenylsilyl; di(C₁ -C₄ alkyl) phenyl silyl; or tri(C₁ -C₄)alkyl silyl; or amono- or disaccharide; wherein R₉ is hydrogen, C₁ -C₅ alkyl; benzoyloptionally substituted with one, 2 or 3 C₁ -C₄ alkyl, C₁ -C₃ alkoxy,halo, C₁ -C₃ alkylthio, trifluoromethyl, nitro; phenyl(C₁ -C₃)alkyloptionally substituted with one, 2 or 3 C₁ -C₄ alkyl, C₁ -C₄ alkoxy,halo, nitro or trifluoromethyl; C₂ -C₆ alkoxyalkyl; C₂ -C₆alkylthioalkyl; C₁ -C₆ alkanoyl; tetrahydropyranyl; C₁ -C₄ alkyldiphenyl silyl; di(C₁ -C₄ alkyl) phenyl silyl; or tri(C₁ -C₄)alkylsilyl; with the overall proviso that either R₇ or R₈ is hydrogen.
 2. Themethod according to claim 1 wherein A is --CH₂.
 3. The method accordingto claim 2 wherein B is --CR₇ R₈ OR₉.
 4. A method of controllinghelminths in animals which comprises administering to an animal aneffective amount, at a dose of about 0.2 to 200 mg/kg of animalbodyweight, of a spiroketal of the formula: ##STR2## wherein A is --CH,or --CH₂ ; wherein . . . is a single bond when A is --CH₂ and a doublebond when A is --CH;wherein B is --CR₇ R₈ OR₉ or --CHO; wherein R₁, R₂,R₄, R₆, and R₈, being the same or different, are hydrogen or C₁ -C₃alkyl; wherein R₇ is hydrogen, C₁ -C₅ alkyl or C₂ -C₆ alkenyl; whereinR₃ is C₁ -C₅ alkyl; benzoyl optionally substituted with one, 2 or 3 C₁-C₄ alkyl, C₁ -C₃ alkoxy, halo, C₁ -C₃ alkylthio, trifluoromethyl,nitro; phenyl(C₁ -C₃)alkyl optionally substituted with one, 2 or 3 C₁-C₄ alkyl, C₁ -C₄ alkoxy, halo, nitro or trifluoromethyl; C₂ -C₆alkoxyalkyl; C₂ -C₆ alkylthioalkyl; C₁ -C₆ alkanoyl; tetrahydropyranyl;C₁ -C₄ alkyl diphenyl silyl; di(C₁ -C₄ alkyl) phenyl silyl; or tri(C₁-C₄)alkyl silyl; wherein R₅ is hydrogen; C₁ -C₅ alkyl; benzoyloptionally substituted with one, 2 or 3 C₁ -C₄ alkyl, C₁ -C₃ alkoxy,halo, C₁ -C₃ alkylthio, trifluoromethyl, nitro; phenyl(C_(1S) -C₃)alkyloptionally substituted with one, 2 or 3 C₁ -C₄ alkyl, C₁ -C₄ alkoxy,halo, nitro or trifluoromethyl; C₂ -C₆ alkoxyalkyl; C₁ -C₆ alkanoyl;tetrahydropyranyl; C₁ -C₄ alkuyl diphenyl silyl; di(C₁ -C₄ alkyl) phenylsilyl; or tri(C₁ -C₄)alkyl silyl; or a mono- or disaccharide; wherein R₉is hydrogen, C₁ -C₅ alkyl; benzoyl optionally substituted with one, 2 or3 C₁ -C₄ alkyl, C₁ -C₃ alkoxy, halo, C₁ -C₃ alkyltio, trifluoromethyl,nitro; phenyl(C₁ -C₃)alkyl optionally substituted with one, 2 or 3 C₁-C₄ alkyl, C₁ -C₄ alkoxy, halo, nitro or trifluoromethyl; C₂ -C₆alkoxyalkyl; C₂ -C₆ alkylthioalkyl; C₁ -C₆ alkanoyl; tetrahydropyranyl;C₁ -C₄ alkyl diphenyl silyl; di(C₁ -C₄ alkyl) phenyl silyl; or tri(C₁-C₄)alkyl silyl; with the overall proviso that either R₇ or R₈ ishydrogen.
 5. The method according to claim 4 wherein A is --CH₂.
 6. Themethod according to claim 4 wherein B is --CR₇ R₈ OR₉.